Software Center not in drop-down list

[Roger Davis <rogerdavis verizon net>]

After updating from 14.04 to 16.04 the Software Center does not appear in the "Applications" Drop-down

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Software Center not in dropdown menu

After updating from 14.04 to 16.04 the Software Center does not appear in the "Applications" drop down in Gnome Metacity or Gnome Compiz. It does appear if I start in straightforward Ubuntu.

I can also start it from the Terminal, using " software-center ". However, after several attempts at getting it to appear on the drop down following several different suggestions, starting from Terminal gets the below: It originally started an apparently newer version (don't have number).
----------------------------------
roger@roger-desktop:~$ software-center
/usr/bin/software-center:25: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, GObject
/usr/share/software-center/softwarecenter/ui/gtk3/views/purchaseview.py:29: PyGIWarning: WebKit2 was imported without specifying a version first. Use gi.require_version('WebKit2', '4.0') before import to ensure that the right version gets loaded.
from gi.repository import WebKit2 as webkit
2016-08-10 21:10:10,342 - softwarecenter.backend.zeitgeist_logger - WARNING - Support for Zeitgeist disabled
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/symbolic_icons.py:23: PyGIWarning: PangoCairo was imported without specifying a version first. Use gi.require_version('PangoCairo', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, Gdk, GLib, PangoCairo
2016-08-10 21:10:10,476 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2016-08-10 21:10:14,717 - softwarecenter.region - WARNING - failed to use geoclue: 'org.freedesktop.Geoclue.Error.notAvailable: Geoclue master client has no usable Address providers'
2016-08-10 21:10:15,379 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2016-08-10 21:10:15,397 - softwarecenter.plugin - INFO - activating plugin '<module 'webapps_activation' from '/usr/share/software-center/softwarecenter/plugins/webapps_activation.pyc'>'
2016-08-10 21:10:15,481 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()
2016-08-10 21:10:15,921 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/videoplayer.py:29: PyGIWarning: Gst was imported without specifying a version first. Use gi.require_version('Gst', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gst
/usr/bin/software-center:184: Warning: Source ID 119 was not found when attempting to remove it
Gtk.main()
/usr/bin/software-center:184: Warning: Source ID 78 was not found when attempting to remove it
Gtk.main()
2016-08-10 21:10:19,086 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
2016-08-10 21:10:20,605 - softwarecenter.db.utils - INFO - software-center-agent finished with status 0
2016-08-10 21:10:20,653 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,680 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,713 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,747 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,784 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,795 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,796 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
2016-08-10 21:10:20,798 - softwarecenter.db.application - WARNING - document no longer valid after db reopen
org.freedesktop.DBus.Error.Spawn.ChildExited: Launch helper exited with unknown return code 1
No handlers could be found for logger "update-software-center-channels"
roger@roger-desktop:~$
VERSION 15.12 APPEARS
---------------------------------------------
SECOND TRY
roger@roger-desktop:~$ software-center
/usr/bin/software-center:25: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, GObject
/usr/share/software-center/softwarecenter/ui/gtk3/views/purchaseview.py:29: PyGIWarning: WebKit2 was imported without specifying a version first. Use gi.require_version('WebKit2', '4.0') before import to ensure that the right version gets loaded.
from gi.repository import WebKit2 as webkit
2016-08-10 21:20:37,604 - softwarecenter.backend.zeitgeist_logger - WARNING - Support for Zeitgeist disabled
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/symbolic_icons.py:23: PyGIWarning: PangoCairo was imported without specifying a version first. Use gi.require_version('PangoCairo', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, Gdk, GLib, PangoCairo
2016-08-10 21:20:37,627 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2016-08-10 21:20:38,435 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2016-08-10 21:20:38,437 - softwarecenter.plugin - INFO - activating plugin '<module 'webapps_activation' from '/usr/share/software-center/softwarecenter/plugins/webapps_activation.pyc'>'
2016-08-10 21:20:38,477 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()
2016-08-10 21:20:38,823 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/videoplayer.py:29: PyGIWarning: Gst was imported without specifying a version first. Use gi.require_version('Gst', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gst
/usr/bin/software-center:184: Warning: Source ID 76 was not found when attempting to remove it
Gtk.main()
/usr/bin/software-center:184: Warning: Source ID 117 was not found when attempting to remove it
Gtk.main()
2016-08-10 21:20:42,075 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
2016-08-10 21:20:43,114 - softwarecenter.db.utils - INFO - software-center-agent finished with status 0
org.freedesktop.DBus.Error.Spawn.ChildExited: Launch helper exited with unknown return code 1
No handlers could be found for logger "update-software-center-channels"
VERSION 15.12 APPEARS
----------------------------------------------
AND DIFFERENT AGAIN...
roger@roger-desktop:~$ software-center
/usr/bin/software-center:25: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, GObject
/usr/share/software-center/softwarecenter/ui/gtk3/views/purchaseview.py:29: PyGIWarning: WebKit2 was imported without specifying a version first. Use gi.require_version('WebKit2', '4.0') before import to ensure that the right version gets loaded.
from gi.repository import WebKit2 as webkit
2016-08-10 21:25:28,308 - softwarecenter.backend.zeitgeist_logger - WARNING - Support for Zeitgeist disabled
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/symbolic_icons.py:23: PyGIWarning: PangoCairo was imported without specifying a version first. Use gi.require_version('PangoCairo', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gtk, Gdk, GLib, PangoCairo
2016-08-10 21:25:28,350 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2016-08-10 21:25:28,829 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2016-08-10 21:25:28,830 - softwarecenter.plugin - INFO - activating plugin '<module 'webapps_activation' from '/usr/share/software-center/softwarecenter/plugins/webapps_activation.pyc'>'
2016-08-10 21:25:28,870 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()
2016-08-10 21:25:29,201 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
/usr/share/software-center/softwarecenter/ui/gtk3/widgets/videoplayer.py:29: PyGIWarning: Gst was imported without specifying a version first. Use gi.require_version('Gst', '1.0') before import to ensure that the right version gets loaded.
from gi.repository import Gst
/usr/bin/software-center:184: Warning: Source ID 70 was not found when attempting to remove it
Gtk.main()
/usr/bin/software-center:184: Warning: Source ID 110 was not found when attempting to remove it
Gtk.main()
2016-08-10 21:25:32,079 - softwarecenter.db.update - WARNING - failed to load file /var/lib/apt-xapian-index/cataloged_times.p: unsupported pickle protocol: 3
2016-08-10 21:25:32,730 - softwarecenter.db.utils - INFO - software-center-agent finished with status 0
org.freedesktop.DBus.Error.Spawn.ChildExited: Launch helper exited with unknown return code 1
No handlers could be found for logger "update-software-center-channels"
VERSION 15.12 APPEARS
----------------------------------------------
And then what appears to be the older version (15.12) appears, where the same command used to get the one that starts in the straightforward Ubuntu log-in - looks very different.

As long as the contents and functions are the same, I don't really care which version appears.

The question(s) are:
1) If the best answer is to simply add it to the drop down, how is this accomplished?
2) If there is another way to make it appear on the drop-down, please let me know how to do this.
3) Do I simply need to reinstall Software Center? If so, how?

Thanks!